Session handling method, communications apparatus, and communications system

Abstract

This application provides a session handling method, a communications apparatus, and a communications system. The session handling method includes receiving, by an intermediate session management function (SMF), a request message sent by an access and mobility management function (AMF), where the request message includes a session identifier, and the intermediate SMF is an SMF selected by the AMF when user equipment (UE) moves outside of a service area of an anchor SMF. When a session corresponding to the session identifier is a local area data network (LADN) session, rejecting, by the intermediate SMF, the session corresponding to the session identifier. According to the technical solutions provided in this application, the user equipment can no longer access a service of a LADN after moving outside of the service area of the anchor SMF, which avoids a waste of service resources of the LADN.

What is claimed is: 
     
       1. A session handling method, comprising:
 receiving, by an anchor session management function, a request message from an intermediate session management function, the request message comprising a session identifier, the intermediate session management function being connected to an access and mobility management function, the intermediate session management function being for serving a user equipment (UE) when the UE moves outside of a service area of the anchor session management function; and 
 in response to a session corresponding to the session identifier being a local area data network (LADN) session, releasing, by the anchor session management function, the session corresponding to the session identifier, wherein a service area of a LADN corresponding to the LADN session is in the service area of the anchor session management function. 
 
     
     
       2. The method according to  claim 1 , wherein the request message is used to request insertion of the intermediate session management function. 
     
     
       3. The method according to  claim 1 , further comprising:
 determining, by the anchor session management function based on a session context, that the session is the LADN session; or 
 determining, by the anchor session management function based on configuration information, that the session is the LADN session, wherein the configuration information comprises: a data network name (DNN) corresponding to the session is a LADN DNN. 
 
     
     
       4. The method according to  claim 1 , further comprising:
 sending, by the anchor session management function, a second message to the intermediate session management function, wherein the second message comprises cause information, and the cause information indicates that the session fails to be activated, or indicates the intermediate session management function to reject activation of the session, or indicates the insertion of the intermediate session management function and an intermediate user plane function is rejected for the LADN session. 
 
     
     
       5. A communications apparatus, comprising:
 at least one hardware processor coupled to a memory; and 
 a communications interface coupled to the at least one hardware processor, 
 the communications interface is configured to receive a request message from an intermediate session management function, the request message comprising a session identifier, and the intermediate session management function being connected to an access and mobility management function, the intermediate session management function being for serving a user equipment (UE) when the UE moves outside of a service area of the communications apparatus, and 
 wherein the at least one hardware processor is configured to, in response to a session corresponding to the session identifier is a local area data network session, release the session corresponding to the session identifier, wherein a service area of the LADN corresponding to the LADN session is in the service area of the communications apparatus. 
 
     
     
       6. The communications apparatus according to  claim 5 , wherein the request message is used to request insertion of the intermediate session management function. 
     
     
       7. The communications apparatus according to  claim 5 , wherein the at least one hardware processor is further configured to:
 determine, based on a session context, that the session is the LADN session; or 
 determine, based on configuration information, that the session is the LADN session, wherein the configuration information comprises: a DNN corresponding to the session is a LADN DNN. 
 
     
     
       8. The communications apparatus according to  claim 5 , wherein the communications interface is further configured to:
 send a second message to the intermediate session management function, wherein the second message comprises cause information, and the cause information indicates that the session fails to be activated, or indicates the intermediate session management function to reject activation of the session, or indicates the insertion of the intermediate session management function and an intermediate user plane function is rejected for the LADN session. 
 
     
     
       9. A communications system, comprising:
 an anchor session management function; and 
 an intermediate session management function, the anchor session management function comprising at least one first hardware processor coupled to a first memory, and the intermediate session management function comprising at least one second hardware processor coupled to a second memory; and 
 the intermediate session management function is configured to send a request message to the anchor session management function, and 
 the anchor session management function is configured to:
 receive the request message from the intermediate session management function, the request message comprising a session identifier, the intermediate session management function being connected to an access and mobility management function, the intermediate session management function being for serving a user equipment (UE) when the UE moves outside of a service area of the anchor session management function; and 
 in response to a session corresponding to the session identifier is a local area data network (LADN) session, release the session corresponding to the session identifier, wherein a service area of the LADN corresponding to the LADN session is in the service area of the anchor session management function. 
 
 
     
     
       10. The communications system according to  claim 9 , further comprising:
 the access and mobility management function, wherein the access and mobility management function comprises at least one third hardware processor coupled to a third memory, and is configured to select the intermediate session management function when the UE moves outside of the service area of the anchor session management function. 
 
     
     
       11. The communications system according to  claim 9 , wherein the anchor session management function is configured to:
 determine, based on a session context, that the session is the LADN session; or 
 determine, based on configuration information, that the session is the LADN session, wherein the configuration information comprises a DNN corresponding to the session is a LADN DNN. 
 
     
     
       12. A session handling method, comprising:
 sending, by an intermediate session management function, a request message to an anchor session management function, the request message comprising a session identifier, the intermediate session management function being connected to an access and mobility management function, the intermediate session management function being for serving a user equipment (UE) when the UE moves outside of a service area of the anchor session management function; 
 receiving, by the anchor session management function, the request message; 
 in response to a session corresponding to the session identifier being a local area data network (LADN) session, releasing, by the anchor session management function, the session corresponding to the session identifier, wherein a service area of a LADN corresponding to the LADN session is in the service area of the anchor session management function. 
 
     
     
       13. The method according to  claim 12 , wherein the request message is used to request insertion of the intermediate session management function. 
     
     
       14. The method according to  claim 12 , further comprising:
 determining, by the anchor session management function based on a session context, that the session is the LADN session; or 
 determining, by the anchor session management function based on configuration information, that the session is the LADN session, wherein the configuration information comprises: a data network name (DNN) corresponding to the session is a LADN DNN. 
 
     
     
       15. The method according to  claim 12 , further comprising:
 sending, by the anchor session management function, a second message to the intermediate session management function, wherein the second message comprises cause information, and the cause information indicates that the session fails to be activated, or indicates the intermediate session management function to reject activation of the session, or indicates the insertion of the intermediate session management function and an intermediate user plane function is rejected for the LADN session; 
 receiving, by the intermediate session management function, the second message. 
 
     
     
       16. The method according to  claim 12 , further comprising:
 selecting, by the access and mobility management function, the intermediate session management function when the UE moves outside of the service area of the anchor session management function. 
 
     
     
       17. The communications apparatus according to  claim 5 , wherein the communications apparatus is an anchor session management function.